Telephone system



Dec-18, 192s. 1,695,312 H. H. ABBOTT Y TELEPHONE SYSTEM Filed April 2o, 1927 2 sheets-sheet 1 W Tram/fr Dec. 18, 1928. l H. H. ABBoTT TELEPHONE SYSTEM Filed April 2o, 1927 v 2 shee'v=,snem` 2 MARS/NAL lies Patented Dec. 18, 1928.

unirsi)y sraras sereni" ori-fics. y

HENRY H. 'A`.B'EO'l"1,` OF NEW YORK, N. Y., ASSIGNORVTO AMERICAN TELEPHONE ANiD' TELEGRAPH COMPANY, A CORPORATION (3F NEW YORK.

TELEPHONE SYSTEM.

Application filed April 20, `1927. Serial No. 185,242.

This invention relates to telephone systems and more particularly to improvements in trunking systems.

According to this invent-ion, a trunking system comprising a plurality oit trunks accessible at one end at a iirst and at a second position and at the other end at a third position is arranged tor checking bythe operator at the third position ot coniiections over said trunks originating at the first position and completed through the second and third positions.

According to one ieatureot the invention, a plurality ot jacks are arranged at the tirst position, a plurality of trunks terminating in plugs at 'the second position, and inv jacks at the third position, with mea-ns whereby the seizure ot' a jack at the iirst position by aV calling subscriber through a link circuit connects said jack throughautomatic switches to an idle trunk and actuates a signal associated with said trunk aty the third position.

According to another feature, an koperators telephone set is automatically connected with a seized trunk at the second positionin response 4to the actuation ot' al-:ey

associated with said trunk at the third position, after said trunk has been seized at the third position. i

According to another' feature, means is provided whereby when the plug at the see,-

ond position is inserted in a. multiple ack of the calling subscriber, a signal is transmitted through the liack at the iirst position to the link circuit for the disconnection of the callingsubscribers line 'from this jack.

, The invention may be applied to a. so-called recording` and completing trunking system in which the recording and"'completing trunks terminate at one end inthe .multiple banks ot' switches associated with recording jacks located atA operators positioi'isand in plugs at toll switching operators positions, While at the other end these trunks terminato-in` jacks. at the-recording and completing operators` positions. lith the invention applied to such asystem, connections from calling*subscribers that are originated through the recording jacksm-ay 'be checked and completed over the trunks trom the recording and completing operators positions to the calling subscriber by way ot the vtoll switching operators" positions,

eording and coinpletingtrunk T.

vtion 'with said trunk system. One recording y and cgonipletin g trunk only has been shown in Fig. l and in l? 1g. Q is shown the opposite end et this trunk terminating at a recording and cempleting operators position. A recording and completing operators cord and the Aincoming end otfa tollline hasfalso been shown in Fig. 2 whereby connections may be completed to wanted subscribers lines.

Referring now to the drawings, a connection may be established rtrom the subscriber of line l tothe toll line 200 or from subscribers having access to line 200 to the subscriber of line l. In establishing a connection from the subscriber or" line ly through, toll lineQOO to a wanted subscriber, the procedure in general yis as follows: The subscriber Ofiline l calls the operator at A' in `the usual` manner, and this operator inserts.

her answering plug 2 ogt the cord A into jack 8- of line 1 Y and determines the type ot connection desired. That is, whether alocal subscriber is wanted or ya subscriber that may only be reached through ya toll connection.

"Ita toll connectionis desired the A operator tests a multiple recording gack'in the usual manner and i'` jackV 5, :torexainplais` idle, inserts Calling plug 4rintovthis jack. This eonuectioi'i causes arronnection to be estab.- lished through switches G with anA idle re- 6 are oit the ordina rily. standard step-by-step continuously rotating type wellknown in the art. `The arrangement 1s' suchthat a plurality ot recording kjacks like 5 and their associated circuitsrare normally `associated Switches with individual'switches like 6 which'have heir brushes normally resting'y on the terminals ot an idle recording;and'fcoinpleting trunkmultiplied to said switches. Aplui-ality suchtrunks may beconnected to i Vnoiv 'lamp 11 is caused to flash.

these switches of a number larger than the number ot switches and their corresponding recording jacks,

Then this connection between an A operators cord and an idle trunk is completed, an

impulse ot ringing' current is transmitted to the distant endet the trunk and this impulse causes a signal 201 to be light-ed to indica-te to thc recording and completing operator otcord lil that a connection desired `over thisy trunli. rihe recording and completing operator answers this call by inserting plug 2011 ot the cord ll into jack Q05 of trunl; T. This causes the usual supervisory signaling in. the il operators cord A to be extinguished, indi eating to the il. operator that the recording and completing'operator is connected to the trunk and ready to receive the information for the completion ot the connection.

The recording and. completing operator asks the calling subscriber for his own number and the number of the wanted subscriber. This information is then recorded in the usual manner and the connection eXA tended by means oit cord l to the Wanted subscriber through toll line 200. The recording ainl` completing operator will now check the number of the calling subscriber by initiatingl a connection by way ot the toll switching o erators position at TS to the calling sul -i scribei"s linel. To this end she operates key 206 and this operation causes various actions to follow. vFirst, the toll switching operators lamp 11 is lighted, second,`the toll switching operators telephone set, not shoivn but indicated as being connected at 10, Will be associated with the trunk rl", third, a tone, :tor example, ot the double zip type, is

transmitted to the rec/ordine and com iletinoy 2D YB operator as an indication that the toll switching operator is ready to receive the information, and fourth, the toll switching operators rlie dashing ot lamp 11 indicates to the toll switching operator that her telephone set is connected to the.

recording and completing operators telephone through the trunk T.

The recording and completing operator Will now pass the number ot the calling" subscribers line to the toll switcliing operator, Whereupon the toll switching` operator causes her tclephone'set to be removed from the trunk T and inserts plug lli ot' this trunk into the multiple jack 15 of the calling subscribers line 1. When this connection isl made, the

ing operatorsposition,the automatic switches associated with other recording` jacks and corresponding to switches 6 will be actuated to advance their brushes to the next idle trunk. A connection is now therefore completed to the subscril'ier of line 1 and the Wanted si1lcswitching operator will be called by the re-r cording and completing operator directly and the recording' jacks and their assoc' ircuits and ap Jaratus are not involved. It should be understood that when a connection ot this type is made, the moment trunk 'Q is talen iter use, the switch 6 and all `other switches associated with the recording jacks will be advanced to connect With the next idle recording and completing trunk. These switches Will therefore always be ready to connect their respective recording aclzs with an idle trunk. v

A more detailed description Will now be made ot a connection from the calling subscriber et line 1 to a Wanted subscriber by Way of toll line i200 and a connection in the opposite direction. When a toll connection is desired from the subscriber of line 1 and the A operator of cord A has inserted plug el into jack 5, an obvious circuit is completed for the operation of relay 17. of this relay causes the operation of relay 21 over a circuit from battery, through 4the Winding of relay 21, inner right hand armature and vfront contact of relay 17, armature and back Contact ot relay 20, to ground. The operation ot relay 21 closesa circuit for the operation ot relayy 22 from battery1 through the left hand armature and back contact ofV relay 28, middle left hand armature and front contact ot relay 21, terminal bank 2&1-, `Winding ot relay 22, to ground.

.The operation of relays 21 and 22 close connections trom the ringing source and ground lat 2G and 27 through the armatures and back contacts ot relay 28, right hand armatures and trent contacts of relay 21, terminal banks 29 and 30, armatures and front contacts of relay 22, tip and ring conductors of trunk T, through the lett hand Winding of ringing' relay 207, condenser 209 and outer left hand' armature back contact of relay 208. The operation of relay 17 also closes an obvious circuit 'for the operation ot relay 32 and this relay in oi'ierating closes a circuit 'for the operation of the relay 33 as follows: battery, winding ot relay 33,

The operation.

ien

opens the circuit for relay and closes a locking circuit for itself through its armature and front contact. When relay 32 releases,

la circuit is completed for relay 28'v from battery, winding of relay 28, armatureand back contact of relay 32, armature'and front Contact of relay`33, to ground vat the arma` ture and back Contact lof relay 20. 'The operation of i'elay28 is therefore delayed for a short interval after the operation of relay 21 to permit theV ringing ,current to be applied to the trunk for the operation of relay 207 for the` corresponding interval. e' Vhen relay 28 does operate the ringing current is removed and the tip and ring conductors are extended through aiinaturesland front contact's of this relay to therelay 35 bridged' across the tip and ringrconductors. L Ringing relayv207 in operating `provides a locking` circuit-for itself controlled by the ground at'the inner upper armature and back contact of `relay '210.' Relayy 207 in operating completes a circuit for the operation of relay 211 as follows: battery/,flower winding of relay 211', varmature and front Contact of relay 207, innergup'perV armature and back contact of relay210, to ground. Relay 211 inoperating closes an obvious circuit for the lighting of 'lamp v201. p The lighting of this lamp indicates to the recording and completing operator that'` a connection is desiredover this trunk. "i

The recording andcompleting operator now answers this call by insertingplug'204 into i ack 205 and thereby completes a circuitV for ythe operation of relayi208. vRelay 208 in operating kopens, the original energizing ycircuit for relay 207 and also "closes a circuit for the operationv of relay-210 as follows: battery, winding of relay 210, upper winding and upper armature and front Contact of relay 211l to ground lat the armature and front contact of relay l208. The operation of relay 210 opens 4the locking lcircuit for relay 207 and the original energizing circuitVV for relay 211.' Relay 207 releases yand it" will be noted that on vthe operation of relay 210 the cicuitthrougli theupper winding of relay 211 willbe short-circuited by the locking circuit for relayf210 which may now betraced from battery,-through thewinding of relay 210, inner lowerarniatur'e and front Contact of this relay, the loop through the y keys 206'and 214 and other similar keys to v ground at the right'hand armature and 'front contact of'relayv208. Key 206 is associated with multiple jack 205 and' key 214 is associated with multiplejack 215;,while other 'similar keys in this loopy circuit are associated with `other corresponding multiple f? `ja'cksat lother positions'.V y1`tela`yf211 is therefore now released and lamp 201 extinguished'. The operation of relay 210 removes the short circuit around condensers 218 and`219 and connects battery to the ring conductor and ground to the tip conductor of trunk T at the upper' and lower outer armatures and lfront contacts of this relay through the windings of relay 220. This-battery vand ground connectioncauses theoperation of relay 35. The circuit through the tip and ring conductors of trunk T extending through both the left and right hand windings ot relay and as the resistance of the'right hand winding is high and relay 220 marginal, this latter relay will not operate at thisr time. lIt vwill be noted that the operation of yrelay '17 has caused the normal short-cii'cuit for the high resistance winding of relay 35 to become 'f opened at the outer right hand armature and back contact of this relay. The voperation of relay 35 closes a circuit 'for the operation of relay 37 as follows; ,b'attery, right hand winding of relay 37arniature`and front co'ntact of rela f inner right hand armature and front contact of relay 17 to ground at the'arinatuie and back contact 'of relay 20.` Relay Y37, inl operating -closes a bridge through the retardation coil B8 for the tip and ring conductors leading to the cord A. This loop circuit causes the operation of the supervisory relay 89 in thercord circuit A and consequently the extinguishing of the supervisory lamp 40. The extinguishing of this lamp indicates to the A operatorthat a `10d recording and completing operators cord is connected to the trunk T.

The recording and completing operator will now connect her telephone set (not shown) to the cord R and ask the calling subscriber Afor the number of the wanted'subscriber and the calling subscribers own nurnbei"-` Vhen the recording operator receives these numbers she will record the call in the usual manner and proceed'to check the number of theV calling subscriber by initiating the extension of a connection to the calling subscriber through the toll switching operators vee iio

position at4 TS. To accomplish this, she will f actuate key 206 associated-with jaclr205 and thus open the holding circuit for relay 210. vRelay 210 in releasing removes" thebattery and ground from the tip'and ring conductors relay 4220 and thiisfsliort circuitsthe condensers 218 and 219 by closinga connection for the tip and ring conductors through the upper and outer lower armatures and back .contacts of this relay. This'is for the purpose of facilitatingv through supervision, as will lay 23. This circuit may-be traced as 'folthat were supplied ythrough the windings of ien i that the stepping magnet 59 Will not operate to advance the brushes ofkswitch 6 as the co1'- responding circuit for relay 2O will not be completed at this time, due `to the operated condition of relay 21.

As the telephone set of the toll switching operator is now connected tothe tip and ring conductors 52 and 53 and trunk T to the recording operators telephone set, this latter operator will now pass the number of the calling subscriber to the toll switching operator. The toll switching operator on receiving this information inserts plug 14 into jack 15 of the calling subscribers line 1.

Y However, previous to the insertionlof this plug into jack 15, she will operate a keyassocial-ed with her telephone set to remove Vher telephone set from the trunk. In accordance with the above mentioned patent to ,lvViley lVhitney, a ground will under these circumstances be connected to lead 55,which as stated, corresponds to lead 11 of the lVliitney application. This ground short-circuits the upper winding of relay 49 so that this relay will now release to disconnect the telephonel set, While relay 50 is maintained operated as hereinbefore described. On the release of relay 49 a circuit will be completed, as soon as plug k14 is inserted in jack 15 and relay 45 is energized through the sleeve circuit, to cause lamp 11 to be shunted. This circuit may be traced as follows: battery, upper outer' armature and back contact of relay 49, upper outer armature and front contact of relay 50, low resistance 66, high resistance 61 to ground. If this circuit had not been closed due to the removal of the toll switching operators telephone set,vthe lamp 11 would have been lightedsteadily on the operation of relay 45 through the circuit established at its lower armature and front contact to ground through the high resistance 61.1f the lamp 11 had lighted steadily it would have indicated to the toll switching operator that she had neglected to remove her telephone Set from the trunk.

The operation of relay 45 opens the above mentioned circuit for maintaining relay 48 operated but as the relay 43 is slow to release and as the subscriber of line 1 has already removed the receiver from the hook, a circuit will be completed on the operation of relay 45 through the tip and ring conductors of the trunl; and the left hand windings of repeatw ing coil 44 and the winding of relay 63, so' that relay 63 in operating will maintain relay 43 operated over a circuit from battery, left hand winding of relay 43, armature and front contact of relay 63, right hand winding of relay 48, to ground at the armature and front contact of relay 42. f

It will be noted that when .relay 43 first operated, a circuit was completed for the operation of relay 65 as follows: battery, winding of relay 65 and its make-beforebreak contacts, inner left hand armature and frontrcontact of Vrelay 21, terminal bank 66, outer right hand armature and front contact of relay 43 to ground. Relay 65 inoperating opens its energizing circuit but completes a lrclring circuit for itselfthrough its right hand armature and front contact to .the ground at the armature and back Contact of 2O.V llelayr65 in operating thus prepared a path for the operation of relay 67 which is completed on the insertion of plug 14 int-o jack 15 as follows: battery, winding of relay 67, left hand armature and front vcontact of relay 65,.terminal bank 69, sleeve terminals of plug 14 and jack 15, to ground. Relay 67 in operating closes an obvious oir' cuit for the operation of relay 70 through an interruptor 7l. rThus,,relay 70 will be alteryie interruptor 71. A circuit will, therefore be alternately'closed and opened for short-circuiting the right hand high resist ymere-ted and released under control tors positionll. The A operator will there fore remove plugs 2 and 4 from jacks 3 and 5, respectively, and in removing plug` 4 from jaclr 5relay 17 will be released. This'relay in releasing opens the holding` circuit completed at its right hand armature and front Contact to the Iground at: the armature and back contact of relay 2O for the release of relays 21, 65, 33 and 28, andirelay 65 in releasing opens the circuits for relays 67 and 7( Hence, all the relays in the circuit asso ciated with reccrdingjaclr 5 and switch 6 will be rel ased.

The swii4 h 6 will now at rance its brushes tov the next idle trunk as the ground at, the armature and front Contact of relay 42 causes the operation of relay 2O and this relay in turn causes the operation of the stepping magnet 59. The connection being now completed between the calling subscriber-s line 1 and the recording and completing operator vat lt, conversation may begin between the subscribers line 1 and the wanted subscribers line connected through toll line 200, that is after the' recording operator has caused t-he connection to this subscriber to be completed'in the usual manner over plug 225 and jaclc226. f

lf trunk T is used as an ordinary toll switchingtrunk for calls originating at the recording and completing operators position, the recording and completing operator will after having received a call from a sub- Illu scriber having access to toll line 200 insert plug 20a into jack 205 to extend the connection'to the Wanted subscriber. The immediate eil'ect of this connect-ion Will be the operation of relay 208. The operation of relay 208 removes4 the ringing relay 207 from across the tip and ring conductors. A circuit is also completed through relay 230 for the operation of relay i2 as hereinbelore de scribed. Relay l2 in operating applies Laround at its armature and frontcontact for the advance of switch 6 and all other switches associated with other recording,` acks to the nent idle trunk. rllhis ground at the armature and 'front contact ot relay also causes the operation of relay i3 and the lighting oi" lamp 1l as well as the automatic connection ot' the toll switching operatofs telephone set to ftrunk'l as hereinbelore described. rllhe connection ot this telephone set to trunk T causes, as hereinbefore described, a double Zip tone to be applied to trunk T to indicate to the recording" and completing1 operator that the toll switching' operatorls telephone set has been connected and also causes the flashing' of lamp 11 to indicate to the toll switching operator that her telephone set has been connected to the trunk T.

The recordingand completing operator will now pass the number of the Wanted sub-` scriber to the toll switching operator and the toll switching operator Will then remove her telephone set from the trunk and insert plugY let into ack l5 oi' the Wanted subscribers line l. The connection to the Wanted subscriber causes the operation of relay d5. Relay l in operating opens the circuit for relay i3 and this relay will noW release to connect bat-l tery and ground through the windings ot relay i2 to the tip and ring conductors of trunk T to cause the lamp 213 to be lighted by the operation of relay 230. @n receiving` this signal the recording and completing operator will apply ringing;l current to the cord R in the usual manner and thuscause the operation of relay 75, and relay 'T5 in oii erating causes the operation ot relay 7G and relay d3. rlhe operation oi' relay i3 maintains relay 4t2 operated during the ringing period and relay 76 applies ringing` cui rent from source 78 to the calling subsoribei"s line` l..

vWhen the called subscriber answers, relay 68 is operated after ringing;v relay 76 isreleased due to the ceasing of the ringing; and relay l2 is thus maintained operated as herinbefore described. Relay di). maintains this trunk busy by applyingnthe `,rround at Y armature and liront Contact toV the bank Wanted subscriber answers relay 68 operates. rhis operates relay i3 which removes battery and ground 'from trunk "l and then the supervisory signal 213 Will be extinguished through the release of 1elay 230. Conversation between the calling` subscriber and the called subscriber may new begin. Y

llllhen the called subscriber hangs up his receiver on the hook, the relay 63 releases causing; the release of relay t3 and thus causes the supervisory signal 21o to be lighted and the recording and complet-ing operator may new take down the connec tion by reniovine' plugs 201i and 225 and jacks 205 and ctively. Upon the removal ol' plug 2li-l, rela-ys and ll will release. i Relay 4t2 in releasing, releases relay 50, and the short circuit through lamp ll is thus removed so that this lamp now lights to indicate to the toll switching operator that disconnection desired. rEhe toll switching operator, by removing plugl lli from jack l5 causes the return oii the circuit at this end of the trunk, to normal.

lt should be infiderstood that the trunkingA su in dcscribcfil in this specification is mer-e` ly illustrative of one application et the inventionY and tl it the various features of the invention f readily be adapted to other systems'he nuo' similar traiiic conditions to meet without departing from the spirit of the in vention.

lVha-t is claimed is:

`l.V ln a telephone system, a trunk accessible ac one end from a. lirst operatoi"s position and terniinating at the same end at a second operator-s position and at the other end at a third operatoids position, a subsoriber7s line having connectingterminals at the `iirst and second positions, a link circuit at the iii-st posit-ion for connecting said subscribers line to said trunk, a signal at the third position, means responsive to the eennection of said link circuit to said trunk for actuating said signal, an operatos telephone setat the second position, .means controlled ir' i tl e tl d position for aut fnatically co1 'tung s d telephonie to the trunk,

naw-s a the second positiin for connecting;

said trunk to said subscribefs line, a s' mal actuatingl the signal at the position.

2. In atelephone system, a irst, a second and a third opcrators position` a plurality of trunks, one end of said trunks terminating at the second position in individual connect-i terminals and t *L ill( trunks at the third position, means responsivet'o the connection of said link circuit with one of' said sets of connecting terminals'at the first position for automatically connecting said set of terminals with an idle trunk through the associated switch and for actuating the signal associated with said trunk at a third position, an operators telephone set at the second position, means controlled from the third positionthrough said trunkfor automatically connecting said telephone set to said trunk, means at the second position for connecting said trunk to said subscribers line, a signal atthe first position, and means responsive to sucha connection at the second v position for actuating the signal at the first position.

3. In a telephone system, a first, a second and a third operators position, a plurality of trunks, one lend of saidtrunks terminating at the second position in individual connecting terminals and at the other end at the third position in individual connecting terminals, a plurality of sets of connecting terminals at the first position, an automatic switch associated with each of said` sets of connecting terminals at the first position, a

lsubscribers line having connecting terminals at the first and second positions, a linkcircuit at the first position for connecting said subscribers line with any set of connecting terminals at this position, a signal associated with each trunk at the third position, means responsive to the connection of said link circuit with one set of connecting terminals at the first position for automatically connecting said set of terminals with an idle trunk through the associated switch and for actuating the signalassociated with said trunk at the third position, an voperators telephone setat the secondv position, means controlled from the third position through said trunk for telephonically disconnecting said set of connecting terminals at the first position from said trunk for automatically actuating all switches except the one associated with the seized set of' terminals at the first position to associate their brushes with the next idle trunk and for automatically connecting said telephone set to said trunk, means at the second position for connecting said trunk to said subscribers line, a signal at the first position, means responsive to such a connection at the second position for actuating said signal at the firstposition, and means responsive to the disconnection of the link circuit'from the seized set ofterminals at the first position for automatically actuating the associated switch to connect it-s brushes with the next idle trunk.

4. In a telephone system, a trunk accessible at one end from a first position and terminating at the same end at a second'position and at the otherend ata-third position, sets of connecting terminals at'the first position, an automatic switch associatedY with each set of'connecting terminals and having access to said trunk, a subscribers line terminating at the first and at vthe second positions, a link circuit at the first position for connecting said subscribersline to any set of connect- Ling terminals thereat, a signal at the third position, means responsive to the seizure of a set of terminals by said link circuit for automatically connecting said set of terminals to the trunk through the associated switch and for actuating said signal, an operators telephone set at the second position, means controlled from the third position for automatically connecting said telephone set to the trunk, means for connecting said subscribers line to the trunk at the second position, a signal'associated with said link circuit, an'd means responsive to the last mentioned connection for actuating said link circuit signal.

5. In a telephone system, a trunk accessible 'at one end frein; a first position and terminating at the same end at a second position, and at the other end at a third position, sets of connecting terminals at the first position, an automatic switch associated with each set of connecting terminals and having access "to said trunk, a subscribers line terminating at the first and at the second positions, a link circuit at the first position for connecting said subscribers line to any set of connecting terminals thereat, a signal at the third position, means responsive to the seizure of a set of terminals by said link circuit for automatically connecting said set of terminals to thetrunk through-the associated switch and for actuating said signal, an operators telephone set at the second position, a key at the third position, means responsive to the actuation of said key for automatically connecting said telephone set to the trunk and for telephonically disconnecting the seized set of terminals at the first position fromthe trunk, means for connecting said subscribers line to the trunk at the second position, a signal associated with said link circuit` and means responsive to the last mentioned connection. for actuating said link circuit signal.

6. In a telephone system, a trunk accessible at one end from a first position and terminating at the same end at a second position and at the other end at a third position, means for `establishing a telephonie connection from the first position to the third position over said trunk, and meansA for establishing a telephonic connection from'the third positionA sition and terminating at the saine end at a second position, and at the other end lat a third position, :i plul'zility of switches, means for establishing a. telephonie connection over 5 any one of said switches from the rst position to an idle trunk, and means for establishing a telephonie connection over said idle trunk from 'the third position to the second position and foi' disabling the i'st mentioned telephonie connection. l 10 In testimony whereof, I have signed my naine to this speoilication this 19th day of April, 1927.

` HENRY H. ABBOTT. 

